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Two novel second-order dual-band bandpass filters (BPFs) with high isolation and high selectivity using coupled lines are realised with a T-shaped bandstop structure. The centre frequencies of the two dual-band BPFs can be adjusted to the desired values by changing the coupling coefficients and characteristic impedances of the two transmission paths. Two dual-band BPFs located at 1.87 and 2.53 GHz and 1.9 and 2.42 GHz are designed and fabricated for demonstration. Good agreements can be observed between simulated and measured performances. [ABSTRACT FROM PUBLISHER]

A compact tri-band bandpass filter using input/output cross coupling is proposed. Three passbands can be adjusted by changing the characteristic impedance of the T-shaped structure with a shorted stub. The three passbands are designed to operate at 1.85, 3.5 and 5.2 GHz based on the T-shaped structure. Four transmission zeros are used to realise high selectivity for the passbands. Good agreement can be observed between the measured and simulated results. [ABSTRACT FROM AUTHOR]

A compact dual-band bandpass filter (BPF) realized with stepped impedance resonators (SIR) and T-shaped line is proposed in this article. By appropriately selecting the impedance ratio of the SIR, a passband around at 5.4 GHz can be achieved by the second harmonic frequency of the SIR. In addition, a T-shaped line is used to replace the quarter-wavelength line between the two SIRs, and another passband at 2.45 GHz is realized between the transmission zeros created by the central open stub of the T-shaped line and the fundamental frequency of the SIR. Moreover, the transmission zeros created by the central open stub and SIR could also be used to improve the skirt selectivity of the proposed BPF. Good agreement can be observed between the measured and simulated results, demonstrating the validity of the design strategies. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2721-2724, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25599 [ABSTRACT FROM AUTHOR]

A high selectivity wideband bandpass filter (BPF) based on transversal signal-interaction concepts and T-shaped structure is proposed in this letter. Two transmission paths with two open coupled lines and a T-shaped structure are used to realize signal transmission from Port 1 to Port 2. A three-order passband with two transmission zeros can be achieved in the proposed filter. One prototype with 3-dB fractional bandwidth of 36.3% (3.3–4.75 GHz) is fabricated for demonstration. Good agreement is observed between simulated and measured performances. [ABSTRACT FROM PUBLISHER]